This application claims benefit of priority under 35 USC 119 to Japanese Patent Application No. P2000-112928 filed on Apr. 14, 2000, the entire contents of which are incorporated by refer herein.
1. Field of the Invention
The present invention relates to a technique of two- or three-dimensionally simulating conditions for manufacturing a semiconductor device, and a method of manufacturing a semiconductor device based on data provided by the simulation. In particular, the present invention relates to a semiconductor device simulation method for handling changes in the geometries of silicide reactive areas, a simulator for achieving the simulation method, and a simulation program for specifying various functions achieved by the simulator.
2. Description of the Related Art
A self-aligned silicide (SALICIDE) process is a semiconductor processing technique to reduce the gate resistance and source/drain resistance of a semiconductor device. The SALICIDE process forms a silicide film on gate electrodes and source/drain diffusion layers in a self-aligning manner. The SALICIDE process employs, for example, cobalt (Co) and involves two step anneal. The first beat treatment uses a relatively low temperature to form a cobalt monosilicide film, i.e., a CoSi film between a Co film and a silicon (Si) material such as a silicon substrate. The second beat treatment uses a relatively high temperature to form a cobalt disilicide film, i.e., a CoSi2 film on the Si material. In this way, the cobalt SALICIDE process forms two silicide films, i.e., CoSi and CoSi2 films having different states and compositions on a silicon material.
A related art simulates the cobalt SALICIDE process by considering only the formation of CoSi2 without paying attention to the formation of CoSi.
This type of related art is described in xe2x80x9cModeling of Local Reduction in TiSi2 and CoSi2 Growth Near Spacers in MOS Technologies: Influence of Mechanical Stress and Main Diffusing Speciesxe2x80x9d by P. Fomara, A. Poncet et. al in IEDM, 1996, pp. 73-76.
FIG. 1 is a flowchart showing the related art of simulating the cobalt SALICIDE process.
Step S51 determines whether or not a cobalt disilicide (CoSi2) film is in contact with the silicon (Si) material, and step S52 determines whether or not the CoSi2 film is in contact with the cobalt (Co) film. If the CoSi2 film is in contact with both the Si material and Co film, step S53 computes a diffusion equation of Co diffusing through CoSi2 and geometry changing equations expressing the geometric changes of the Co film, CoSi2 film, and Si material, and changes the geometries of the Co film, CoSi2 film, and Si material accordingly.
Step S54 increments time by xcex94t. Step S55 determines whether or not a predetermined heat treatment time has passed. If not, the flow returns to step S51, and steps S51 to S53 are repeated at intervals of xcex94t. If step S55 determines that the predetermined heat treatment time has passed, the simulation provides final element geometries.
As mentioned above, the actual SALICIDE process involves a first heat treatment of forming CoSi and a second heat treatment of forming CoSi2. However, the related art simulates only the formation of CoSi2 based on one of the first and second heat treatments. CoSi and CoSi2 are formed through different physical phenomena, and if the CoSi forming stage is ignored, silicide reactions will incorrectly be simulated. In particular, the related art involves inaccuracy when simulating silicide film thicknesses and element geometries in the SALICIDE process by using different heat treatment conditions.
The related art also involves inaccuracy when calculating interface movements caused by silicide reactions. This leads to inaccurate calculations of stress and point defects caused in a silicon material due to the interface movements.
An object of the present invention is to provide a simulation method capable of correctly simulating silicide film thicknesses and element geometries, allowing the speedy selection of proper process parameters, reducing the numbers of prototypes and tests, shortening a development period, and improving development efficiency. Also provided are a simulator for executing the simulation method, a simulation program for realizing functions of the simulation method, and a semiconductor manufacturing method employing the simulation method.
In order to accomplish the objects, a first aspect of the present invention provides a simulation method comprising a first step of determining whether or not a silicide region (which may be in the form of a film and is made of a metal and silicon) is in contact with a silicon region (which is made of silicon) and a metal region (which may be in the form of a film and is made of this metal); a second step of determining, if the silicide region is in contact with the metal and silicon regions, the species diffusing through the silicide region according to a temperature heating the silicide, metal, and silicon regions and the composition of the silicide region; a third step of finding, if the species diffusing rough the silicide region is silicon, it""s positional relationships among the metal, silicide, and silicon regions according to a first diffusion equation expressing diffusion of silicon through the silicide region and geometry changing equations expressing geometric changes of the metal, silicide, and silicon regions; and a fourth step of finding, if the species diffusing through the silicide region is the metal, positional relationships among the metal, silicide, and silicon regions according to a second diffusion equation expressing diffusion of the metal through the silicide region and geometry changing equations expressing geometric changes of the metal, silicide, and silicon regions.
The composition of the silicide region is expressed as MySix where x and y indicate a coupling state of metal M and silicon Si that form the silicide.
The first aspect of the present invention simulates the SALICIDE process by separately considering silicide reactions caused by first and second heat treatments. This reduces the number of process parameters, prototypes and tests, shortens the development period, and improves development efficiency.
A second aspect of the present invention provides a simulator having first means for determining whether or not a silicide region (which may be in the form of a film and is made of a metal and silicon) is in contact with a silicon region (which is made of silicon) and a metal region (which may be in the form of a film and is made of this metal); second means for determining, if the silicide region is in contact with the metal region and the silicon region, the species diffusing through the silicide region according to a temperature heating the silicide, metal and silicon regions and the composition of the silicide region; third means for finding, if the species diffusing through the silicide region is silicon, it""s positional relationships among the silicide, metal, and silicon regions according to a first diffusion equation expressing diffusion of silicon through the silicide region and geometry changing equations expressing geometric changes of the silicide, metal, and silicon regions; and fourth means for finding, if the species diffusing through the silicide region is the metal, it""s positional relationships among the silicide, metal, and silicon regions according to a second diffusion equation expressing the diffusion of the metal through the silicide region and geometry changing equations expressing geometric changes of the silicide, metal, and silicon regions.
The simulator of the second aspect accurately calculates silicide region thicknesses and element geometries, reduces the number of pros parameters, prototypes, and tests, shortens a development period, and increases development efficiency.
A third aspect of the present invention provides a simulation program having a first computer readable program code which determines whether or not a silicide region (which may be in the form of a film and is made of a metal and silicon) is in contact with a silicon region (which is made of silicon) and a metal region (which may be in the form of a film and is made of this metal); a second computer readable program code which determines, if the silicide region is in contact with the metal and the silicon regions, the species diffusing through the silicide region according to a temperature heating the silicide, metal, and silicon regions and the composition of the silicide region; a third computer readable program code which finds, if the species diffusing through the silicide region is silicon, positional relationships among the silicide, metal, and silicon regions according to a first diffusion equation expressing diffusion of silicon through the silicide region and geometry changing equations expressing geometric changes of the silicide, metal, and silicon regions; and a fourth computer readable program code which finds, if the species diffusing through the silicide region is the metal, positional relationships among the silicide, metal, and silicon regions according to a second diffusion equation expressing diffusion of the metal through the silicide region and geometry changing equations expressing geometric changes of the silicide, metal, and silicon regions.
The third aspect of the simulation program accurately calculates silicide region thicknesses and element geometries, reduces the number of process parameters, prototypes, and tests, shortens a development period, and increases development efficiency.
A fourth aspect of the present invention provides a method of manufacturing a semiconductor device, having a first procedure including a first act of determining whether or not a silicide region (which may be in the form of a film and is made of a metal and silicon) is in contact with a silicon region (which is made of silicon) and a metal region (which may be in the form of a film and is made of the metal); a second act of determining, if the silicide region is in contact with the metal and silicon regions, the species diffusing through the silicide region according to a temperature heating the silicide, metal, and silicon regions and the composition of the silicide region; a third act of finding, if the species diffusing through the silicide region is silicon, positional relationships among the silicide, metal, and silicon regions according to a first diffusion equation expressing diffusion of silicon through the silicide region and geometry changing equations expressing geometric changes of the silicide, metal, and silicon regions; and a fourth act of finding, if the species diffusing though the silicide region is the metal, positional relationships among the silicide, metal, and silicon regions according to a second diffusion equation expressing the diffusion of the metal through the silicide region and geometry changing equations expressing geometric changes of the silicide, metal, and silicon regions; a second procedure of finding the electric characteristics of the semiconductor device according to given electric boundary conditions and semiconductor element structural data based on the found positional relationships among the silicide, metal, and silicon regions; and a third procedure of executing a series of manufacturing processes including a silicide process on a semiconductor material according to a result of evaluation of the found electric characteristics, thereby manufacturing the semiconductor device.
The fourth aspect of the semiconductor device manufacturing method drastically shortens a period from study (designing) to development including precision simulations of a semiconductor device.
Other and further objects and features of the present invention will become obvious upon an understanding of the illustrative embodiments about to be described in connection with the accompanying drawings or will be indicated in the appended claims, and various advantages not referred to herein will be apparent to one skilled in the art upon employing of the invention in practice.